1. Field of the Invention
This invention relates generally to the manufacture of seat cushions, and more particularly to seat cushions for use in wheelchairs.
2. Description of the Prior Art
Recent advances in the rehabilitation technology have improved products available which cushion and support a person while seated. Maintaining a functional seated posture for a long period of time requires special support to prevent pressure sores, which are more commonly known as bed sores. Pressure sores arise from bony protuberances which cause areas of excessive pressure restricting blood flow to the surrounding tissue. Appropriate body support is required to provide protection from pressure sores and to prevent poor circulation and enhance functional capabilities of those restricted to the seated position.
Custom-made contoured cushions have been recognized as providing the support and comfort necessary for those who remain seated for extended periods. Various approaches have been undertaken to fabricate contoured seating cushions which provide the desired support and comfort. Primarily, the advancement in the art in the design and manufacture of customized cushions has been in the manner of measuring a patient's contour for a custom-made cushion, such as the devices and methods disclosed in U.S. Pat. No. 4,890,235 to Reger et al.; U.S. Pat. No. 4,972,351 to Reger et al.; U.S. Pat. No. 4,998,354 to Silverman et al.; and U.S. Pat. No. 5,193,285 to Heinrich et al.
Generally speaking, seat contour data is obtained by the patient sitting on a mechanical or an electro/mechanical profile measuring device. Then the data is converted into a seat profile. One such computer program that converts the raw data into a seat cushion profile is Seat Maker.TM. software developed by Pin Dot Products. The converted data can then be sent to a numerically controlled computer aided milling machine, which in turn machines a foam custom fit cushion from the input data. This is a very expensive process and very time-consuming. Furthermore, there is a substantial amount of waste in the foam cushion.
Another method for manufacturing custom contoured seat cushions is disclosed in U.S. Pat. No. 4,763,951 to Silverman, where a cushion profile is made by a patient sitting on a "bean bag" type seat. A vacuum is drawn on the seat making an impression of a contoured seating cushion. Subsequently, plaster impregnated gauze strips are laid over the impression forming mold. This mold is then sent to a fabricator which then uses that mold to make a foam seat cushioned by pouring a foamable material into the plaster impression and then removing the impression. This method is extremely labor intensive, and in turn results in an expensive seat cushion.
Yet another method for manufacturing a custom contoured seat cushion is set forth in U.S. Pat. No. 4,828,325 to Brooks. This patent discloses a method upon which a patient is placed upon a molding device having a deformable upper surface defining a molding cavity. Then a foamable material is injected into the molding cavity to form a foam custom contoured seat cushion. One problem with the device as disclosed in the Brooks patent is that various computer techniques, such as that of the Seat Maker.TM. software program, are not available to customize the cushion.
Accordingly, it is an object of the invention to economically and quickly manufacture custom seat cushions.
The object is achieved through many unique features of the present invention, such as the use of a device to form a positive profile, a device to form a negative profile, utilizing a plurality of rods to define the profile, the use of gravitational forces to assist in the formation of the positive profile, and the use of a computer to determine the positive profile shape and to control the device to form a positive profile.